To get Jekyll to work in heroku, run this command after creating the project in heroku:
Specifically, if you see this:
remote: ! Push rejected, no Cedar-supported app detected
remote: HINT: This occurs when Heroku cannot detect the buildpack
remote: to use for this application automatically.
remote: See https://devcenter.heroku.com/articles/buildpacks
Use this command:
heroku config:add BUILDPACK_URL=https://github.com/andycroll/heroku-buildpack-jekyll
And follow the rest of the comments in this blog post:
http://andycroll.com/ruby/serving-a-jekyll-blog-using-heroku/